TOKYO - Chinese Ambassador to Japan Cheng Yonghua on Tuesday protested against that Japan's intrusion into surrounding waters of the Diaoyu Islets and demanded that all Japanese ships leave the waters immediately, according to the Chinese embassy in Japan.

Cheng lodged the protest during his meeting with Japanese vice-Foreign Minister Chikao Kawai and rejected Japan's protest over Chinese surveillance ships entering into the waters, said the embassy in its website.

Cheng emphasized the Diaoyu Islands and its surrounding waters are Chinese inherent territories and the Chinese surveillance ships were on regular patrol duty.

Earlier Tuesday, several Japanese boats were spotted in waters around the islands and about eight Chinese marine surveillance ships monitored the intruding Japanese ships from different angles, according to China's State Oceanic Administration.